On-board person load sensor

ABSTRACT

An occupant load sensor ( 10 ) is fixed to a bracket ( 48 ) via a sleeve ( 60   a ) of a collar ( 60 ) arranged in an outer periphery of a thread ( 32 ) of a bolt portion ( 30 ), and a bush ( 62 ) interposed between the sleeve ( 60   a ) and a through hole ( 48   a ) of the bracket ( 48 ). Accordingly, a slight movement is allowed between the bolt portion ( 30 ) and the bracket ( 48 ) on the basis of gaps formed between the thread ( 32 ) and the sleeve ( 60   a ) and between the sleeve ( 60   a ) and the bush ( 62 ), and it is possible to cancel a force applied from the other directions than a vertical direction. Therefore, a load from the seat side is applied in the vertical direction and it is possible to accurately detect.

TECHNICAL FIELD

The present invention relates to an occupant load sensor measuring aweight of an occupant seated on a seat of a vehicle.

BACKGROUND ART

In order to secure a safety of the occupant, a seat belt and an air bagare provided in a motor vehicle. In recent years, in order to furtherimprove a safety, an operation of the seat belt and the air bag iscontrolled by identifying an adult or a child, and further in conformityto the weight of the occupant. In particular, in the case that theoccupant is an adult, a pretension of the air bag and the seat belt isactuated, and in the case that the occupant is a child, the pretensionis not actuated. Alternatively, a developing gas amount and a developingspeed of the air bag are adjusted and the pretension of the seat belt isadjusted in conformity to the weight of the occupant.

The identification whether the occupant is an adult or a child mentionedabove is generally executed by detecting the weight by an occupant loadsensor attached to a seat. As the occupant load sensor mentioned above,there are, for example, JP 11-351952 A (publication 1), JP 11-1153 A(publication 2) and JP 9-207638 A (publication 3). In each of thepublications, four occupant load sensors are arranged in four cornersbetween a floor side seat fixing member (for example, a rail mount) anda seat side fixing member (for example, a seat rail), whereby the weightof the occupant (load) is measured.

In this case, it is necessary to firmly fix the seat for the vehicle toa floor in such a manner as to be prevented from coming off at a time ofan accident. In the publications 2 and 3, there is provided a structurein which the occupant load sensor is arranged between the floor sideseat fixing member (for example, the rail mount) and the seat sidefixing member (for example, the seat rail), and there is a risk that theoccupant load sensor is broken at a time of the accident and the seatfalls away. On the other hand, in the publication 1, it is intended toprevent the seat from falling away at a time of the accident byarranging a displacement regulating mechanism in addition to theoccupant load sensor, however, there is a problem that the structurebecomes complicated and a manufacturing cost is increased due to theindependently provided displacement regulating mechanism.

In order to do away with the displacement regulating mechanism so as torestrict the manufacturing cost, the occupant load sensor can bestructured, for example, as shown in FIG. 15 in place of the structurein which the seat is reciprocated vertically and the load is applied toa sensor plate as in the publication 1. FIG. 15A shows a front view ofthe occupant load sensor, and FIG. 15B shows a cross section along aline B4-B4 in FIG. 15A. An occupant load sensor 110 is constituted by amain body portion 120 receiving a displacement sensor 112, an upper boltportion 132 fixed, for example, to a seat rail side, and a lower boltportion 134 fixed to a rail mount side. A strain surface 114 allowed tobe deflected microscopically by the load is provided within the mainbody portion 120, and the displacement sensor 112 is arranged in thestrain surface 114. In this structure, since it is not necessary tovertically reciprocate the seat, it is possible to obtain a necessaryseat strength by manufacturing an entire occupant load sensor by a metalwithout using the displacement regulating mechanism as in thepublication 1.

However, in the structure shown in FIG. 15, in the case that an accuracyof an attaching position of the seat rail with respect to the floor siderail mount is low, the occupant load sensor is attached in a state inwhich the occupant load sensor is inclined, and in a state in which aforce in the other directions than a vertical direction is applied, sothat there is a problem that a measuring accuracy is lowered.

The present invention is made for the purpose of solving the problemmentioned above, and an object of the present invention is to provide anoccupant load sensor which can improve a detecting performance on thebasis of a simple structure.

DISCLOSURE OF THE INVENTION

In order to solve the above problem, according to Claim 1, an occupantload sensor interposed between a floor side seat fixing member and aseat side fixing member and provided for measuring a load of an occupantsitting on a seat, comprising:

a flange portion which is attached to one of said floor side seat fixingmember and said seat side fixing member while being in surface contactthere with;

a bolt portion which is formed in a vertical direction with respect tosaid flange portion, and is attached to the other of said floor sideseat fixing member and said seat side fixing member via a nut; and

a sensor which is arranged in a strain surface provided between saidflange portion and said bolt portion, and is provided for detecting aload applied to said bolt portion in an axial direction.

In accordance with a first aspect, the occupant load sensor is attachedto one of the floor side seat fixing member and the seat side fixingmember while being in surface contact with the fixing member by theflange portion, and the bolt portion formed in the vertical direction tothe flange portion is attached to the other of the floor side seatfixing member and the seat side fixing member via a nut. Accordingly,the load from the seat is applied in the vertical direction, and it ispossible to measure the load by the sensor. Further, it is possible tolower a hip point of the seat by receiving the flange portion within anupper rail or a lower rail.

According to Claim 2, an occupant load sensor interposed between a floorside seat fixing member and a seat side fixing member and provided formeasuring a load of an occupant sitting on a seat, wherein said occupantload sensor comprising:

a fixing portion which is attached to one of said floor side seat fixingmember and said seat side fixing member;

a bolt portion which is inserted to a through hole in the other of saidfloor side seat fixing member and said seat side fixing member and isattached via a nut; and

a sensor which is arranged in a strain surface provided between saidfixing portion and said bolt portion, and is provided for detecting aload applied to said bolt portion in an axial direction, and

wherein said occupant load sensor is fixed to the other of said floorside seat fixing member and said seat side fixing member via a sleevearranged in an outer periphery of said bolt portion, and a liner memberinterposed between said sleeve and the through hole in the other of saidfloor side seat fixing member and said seat side fixing member.

In accordance with a second aspect, the occupant load sensor is fixed tothe other of the floor side seat fixing member and the seat side fixingmember via the sleeve arranged in the outer periphery of the boltportion, and the liner member interposed between the sleeve and thethrough hole in the other of the floor side seat fixing member and theseat side fixing member. Accordingly, a slight motion can be allowedbetween the bolt portion and the other of the floor side seat fixingmember and the seat side fixing member to which the bolt portion isfixed, on the basis of the gap formed between the bolt portion and thesleeve, and the gap between the sleeve and the liner member, and it ispossible to cancel the force applied from the other directions than thevertical direction. Therefore, the load from the seat side is applied tothe sensor in the vertical direction, and it is possible to accuratelydetect the load. Further, even if the accuracy of the attaching positionof the seat side fixing member with respect to the floor side seatfixing member is low, and the occupant load sensor is attached in astate in which the force in the other directions than the verticaldirection is applied, the load from the seat side is applied to thesensor in the vertical direction and it is possible to accurately detectthe load because the slight motion is allowed between the bolt portionand the other of the floor side seat fixing member and the seat sidefixing member.

According to Claim 3, an occupant load sensor interposed between a floorside seat fixing member and a seat side fixing member and provided formeasuring a load of an occupant sitting on a seat, wherein said occupantload sensor comprising:

a flange portion which is attached to one of said floor side seat fixingmember and said seat side fixing member while being in surface contacttherewith;

a bolt portion which is formed in a vertical direction with respect tosaid flange portion and is attached to the other of said floor side seatfixing member and said seat side fixing member via a nut; and

a sensor which is arranged in a strain surface provided between saidflange portion and said bolt portion, and is provided for detecting aload applied to said bolt portion in an axial direction, and whereinsaid occupant load sensor is fixed to the other of said floor side seatfixing member and said seat side fixing member via a sleeve arranged inan outer periphery of said bolt portion, and a bush interposed betweensaid sleeve and a through hole in the other of said floor side seatfixing member and said seat side fixing member.

In accordance with a third aspect, the occupant load sensor is fixed tothe other of the floor side seat fixing member and the seat side fixingmember via the sleeve arranged in the outer periphery of the boltportion, and the liner member interposed between the sleeve and thethrough hole in the other of the floor side seat fixing member and theseat side fixing member. Accordingly, a slight motion can be allowedbetween the bolt portion and the other of the floor side seat fixingmember and the seat side fixing member to which the bolt portion isfixed, on the basis of the gap formed between the bolt portion and thesleeve, and the gap between the sleeve and the liner member, and it ispossible to cancel the force applied from the other directions than thevertical direction. Therefore, the load from the seat side is applied tothe sensor in the vertical direction, and it is possible to accuratelydetect the load. Further, even if the accuracy of the attaching positionof the seat side fixing member with respect to the floor side seatfixing member is low, and the occupant load sensor is attached in astate in which the force in the other directions than the verticaldirection is applied, the load from the seat side is applied to thesensor in the vertical direction and it is possible to accurately detectthe load because the slight motion is allowed between the bolt portionand the other of the floor side seat fixing member and the seat sidefixing member. In particular, the occupant load sensor is attached toone of the floor side seat fixing member and the seat side fixing memberwhile being in surface contact with the fixing member by the flangeportion, and the bolt portion formed in the vertical direction to theflange portion is attached to the other of the floor side seat fixingmember and the seat side fixing member via a nut. Accordingly, the loadfrom the seat is applied in the vertical direction, and it is possibleto accurately measure the load by the sensor.

According to Claim 4, an occupant load sensor interposed between a floorside seat fixing member and a seat side fixing member and provided formeasuring a load of an occupant sitting on a seat, wherein said occupantload sensor comprising:

a flange portion which is attached to one of said floor side seat fixingmember and said seat side fixing member while being in surface contacttherewith;

a bolt portion which is formed in a vertical direction with respect tosaid flange portion and is attached to the other of said floor side seatfixing member and said seat side fixing member via a nut; and

a sensor which is arranged in a strain surface provided between saidflange portion and said bolt portion, and is provided for detecting aload applied to said bolt portion in an axial direction, and

wherein said occupant load sensor is fixed to the other of said floorside seat fixing member and said seat side fixing member via a sleevearranged between said bolt portion and a through hole in the other ofsaid floor side seat fixing member and said seat side fixing member, anda flat washer inserting said sleeve therethrough and interposed betweenthe other of said floor side seat fixing member and said seat sidefixing member and a nut.

In accordance with a fourth aspect, the occupant load sensor is fixed tothe other of the floor side seat fixing member and the seat side fixingmember via the sleeve arranged in the bolt portion and the through holein the other of the floor side seat fixing member and the seat sidefixing member, and the flat washer inserting the sleeve therethrough andinterposed between the other of the floor side seat fixing member andthe seat side fixing member and the nut. Accordingly, a slight motioncan be allowed between the bolt portion and the other of the floor sideseat fixing member and the seat side fixing member to which the boltportion is fixed, on the basis of the gap formed between the boltportion and the sleeve, and the gap formed between the other of thefloor side seat fixing member and the seat side fixing member in whichthe flat washer is interposed and the nut, and it is possible to cancelthe force applied from the other directions than the vertical direction.Therefore, the load from the seat side is applied to the sensor in thevertical direction, and it is possible to accurately detect the load.Further, even if the accuracy of the attaching position of the seat sidefixing member with respect to the floor side seat fixing member is low,and the occupant load sensor is attached in a state in which the forcein the other directions than the vertical direction is applied, the loadfrom the seat side is applied to the sensor in the vertical directionand it is possible to accurately detect the load because the slightmotion is allowed between the bolt portion and the other of the floorside seat fixing member and the seat side fixing member. In particular,the occupant load sensor is attached to one of the floor side seatfixing member and the seat side fixing member while being in surfacecontact with the fixing member by the flange portion, and the boltportion formed in the vertical direction to the flange portion isattached to the other of the floor side seat fixing member and the seatside fixing member via a nut. Accordingly, the load from the seat isapplied in the vertical direction, and it is possible to accuratelymeasure the load by the sensor.

In the second aspect to the fourth aspect, it is preferable that thesleeve is a part of the collar. Since the flange of the collar isbrought into contact with the other of the floor side seat fixing memberand the seat side fixing member to which the bolt portion is fixed, andthe load in the axial (vertical) direction is generated with respect tothe sleeve, the load from the seat is applied in the vertical direction,and it is possible to accurately measure the load by the sensor.Further, the number of the parts is small and it is easy to assemble.

In the first aspect to the fifth aspect, it is preferable that a pair offloor side seat fixing members are connected via the bracket. A relativeattaching position of a pair of floor side seat fixing members is notdisplaced on the basis of the connection by the bracket, and it ispossible to prevent the occupant load sensor from being attached betweenthe floor side fixing member and the seat side fixing member in a statein which the force in the other directions than the vertical directionis applied.

In order to solve the above problem, according to Claim 7, an occupantload sensor interposed between a floor side seat fixing member and aseat side fixing member and provided for measuring a load of an occupantsitting on a seat, comprising:

a flange portion which is provided with a plurality of screw holes forfastening by bolts and is attached to one of said floor side seat fixingmember and said seat side fixing member while being in surface contacttherewith;

an attaching portion which is formed in a vertical direction withrespect to said flange portion, and is attached to the other of saidfloor side seat fixing member and said seat side fixing member; and

a sensor which is provided for detecting a load applied to saidattaching portion in an axial direction,

wherein at least one of a plurality of screw holes provided in saidflange portion is fastened by bolts so as to allow a motion between saidflange portion and one of said floor side seat fixing member and saidseat side fixing member.

In accordance with a seventh aspect, it is possible to make the torsionof one of the floor side seat fixing member and the seat side fixingmember hard to be transmitted to the occupant load sensor, by allowing apart of the flange portion to move. Accordingly, the load from the seatside is applied to the sensor in the vertical direction, and it ispossible to accurately detect the load. Further, even if the occupantload sensor is attached in the state in which the accuracy of theattaching portion of the seat side fixing member with respect to thefloor side seat fixing member is low, and the force in the otherdirections than the vertical direction is applied, the load from theseat side is applied to the sensor in the vertical direction and it ispossible to accurately detect the load because the slight motion isallowed between a part of the flange portion and one of the floor sideseat fixing member and the seat side fixing member.

According to Claim 8, an occupant load sensor interposed between a floorside seat fixing member and a seat side fixing member and provided formeasuring a load of an occupant sitting on a seat, comprising:

a flange portion which is provided with a plurality of screw holes forfastening by bolts and is attached to one of said floor side seat fixingmember and said seat side fixing member while being in surface contacttherewith;

a bolt portion which is formed in a vertical direction with respect tosaid flange portion, and is attached to the other of said floor sideseat fixing member and said seat side fixing member via a nut; and

a sensor which is provided for detecting a load applied to said boltportion in an axial direction,

wherein one of a plurality of screw holes provided in said flangeportion is fixed by a shoulder bolt provided with a step portion higherthan a thickness of one of said floor side seat fixing member and saidseat side fixing member, whereby an air gap is provided between a headof the shoulder bolt and one of said floor side seat fixing member andsaid seat side fixing member.

In accordance with an eighth aspect, the slight motion is allowedbetween the shoulder bolt fixing portion of the flange portion and oneof the floor side seat fixing member and the seat side fixing member towhich the flange portion is fixed, on the basis of the air gap (the gap)formed between the head of the shoulder bolt and one of the floor sideseat fixing member and the seat side fixing member, and it is possibleto make the torsion of one of the floor side seat fixing member and theseat side fixing member hard to be transmitted to the occupant loadsensor. Accordingly, the load from the seat side is applied to thesensor in the vertical direction, and it is possible to accuratelydetect the load. Further, even if the accuracy of the attaching positionof the seat side fixing member with respect to the floor side seatfixing member is low, and the occupant load sensor is attached in astate in which the force in the other directions than the verticaldirection is applied, the load from the seat side is applied to thesensor in the vertical direction and it is possible to accurately detectthe load because the slight motion is allowed between the shoulder boltfixing portion of the flange portion and one of the floor side seatfixing member and the seat side fixing member. Further, the occupantload sensor is attached to one of the floor side seat fixing member andthe seat side fixing member while being in surface contact with thefixing member by the flange portion, and the bolt portion formed in thevertical direction to the flange portion is attached to the other of thefloor side seat fixing member and the seat side fixing member via thenut. Accordingly, the load from the seat is applied in the verticaldirection, and it is possible to accurately measure the load by thesensor.

According to Claim 9, an occupant load sensor, wherein a occupant loadsensor is fixed to the other of a floor side seat fixing member and aseat side fixing member via a sleeve arranged in an outer periphery of abolt portion, and a bush interposed between a sleeve and a through holein the other of a floor side seat fixing member and a seat side fixingmember. Accordingly, the slight motion can be allowed between the boltportion and the other of the floor side seat fixing member and the seatside fixing member to which the bolt portion is fixed, on the basis ofthe gap formed between the bolt portion and the sleeve, and the gapformed between the sleeve and the bush, and it is possible to cancel theforce applied from the other directions than the vertical direction.Therefore, the load from the seat side is applied to the sensor in thevertical direction, and it is possible to accurately detect the load.Further, even if the accuracy of the attaching position of the seat sidefixing member with respect to the floor side seat fixing member is low,and the occupant load sensor is attached in the state in which the forcein the other directions than the vertical direction is applied, the loadfrom the seat side is applied to the sensor in the vertical directionand it is possible to accurately detect the load because the slightmotion is allowed between the bolt portion and the other of the floorside seat fixing member and the seat side fixing member. In particular,the occupant load sensor is attached to one of the floor side seatfixing member and the seat side fixing member while being in surfacecontact with the fixing member by the flange portion, and the boltportion formed in the vertical direction to the flange portion isattached to the other of the floor side seat fixing member and the seatside fixing member via the nut. Accordingly, the load from the seat isapplied in the vertical direction, and it is possible to accuratelymeasure the load by the sensor.

According to Claim 10, an occupant load sensor, wherein a occupant loadsensor is fixed to the other of a floor side seat fixing member and aseat side fixing member via a sleeve arranged between a bolt portion anda through hole in the other of a floor side seat fixing member and aseat side fixing member, and a flat washer inserting a sleevetherethrough and interposed between the other of a floor side seatfixing member and a seat side fixing member and the nut.

Accordingly, the slight motion can be allowed between the bolt portionand the other of the floor side seat fixing member and the seat sidefixing member to which the bolt portion is fixed, on the basis of thegap formed between the bolt portion and the sleeve, and the gap formedbetween the other of the floor side seat fixing member and the seat sidefixing member in which the flat washer is interposed and the nut, and itis possible to cancel the force applied from the other directions thanthe vertical direction. Therefore, the load from the seat side isapplied to the sensor in the vertical direction, and it is possible toaccurately detect the load. Further, even if the accuracy of theattaching position of the seat side fixing member with respect to thefloor side seat fixing member is low, and the occupant load sensor isattached in a state in which the force in the other directions than thevertical direction is applied, the load from the seat side is applied tothe sensor in the vertical direction and it is possible to accuratelydetect the load because the slight motion is allowed between the boltportion and the other of the floor side seat fixing member and the seatside fixing member. In particular, the occupant load sensor is attachedto one of the floor side seat fixing member and the seat side fixingmember while being in surface contact with the fixing member by theflange portion, and the bolt portion formed in the vertical direction tothe flange portion is attached to the other of the floor side seatfixing member and the seat side fixing member via a nut. Accordingly,the load from the seat is applied in the vertical direction, and it ispossible to accurately measure the load by the sensor.

In the ninth aspect to the eleventh aspect, it is preferable that thesleeve is a part of the collar. Since the flange of the collar isbrought into contact with the other of the floor side seat fixing memberand the seat side fixing member to which the bolt portion is fixed, andthe load in the axial (vertical) direction is generated with respect tothe sleeve, the load from the seat is applied in the vertical direction,and it is possible to accurately measure the load by the sensor.Further, the number of the parts is small and it is easy to assemble.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a plan view of an occupant load sensor in accordance with afirst embodiment;

FIG. 1B is a side elevational view;

FIG. 1C is a cross sectional view along a line C-C in FIG. 1A;

FIG. 2A is a plan view of a state in which a terminal box is attached tothe occupant load sensor in accordance with the first embodiment;

FIG. 2B is a side elevational view;

FIG. 3A is an explanatory view of an attachment of the occupant loadsensor;

FIG. 3B is a cross sectional view along a line B-B in FIG. 4A;

FIG. 4B is a side elevational view of a seat rail 40 shown in FIG. 14Aas seen from an arrow B side;

FIG. 4A is a cross sectional view along a line A1-A1 in FIG. 4B;

FIG. 5B is a side elevational view showing a state in which the occupantload sensor in accordance with the first embodiment is attached to aseat rail in accordance with the other example;

FIG. 5A is a cross sectional view along a line A2-A2 in FIG. 5B;

FIG. 6B is a side elevational view showing a state in which the occupantload sensor in accordance with the first embodiment is attached to aseat rail in accordance with further the other example;

FIG. 6A is a cross sectional view along a line A3-A3 in FIG. 6B;

FIG. 7A is a plan view of an occupant load sensor in accordance with theother example of the first embodiment;

FIG. 7B is a cross sectional view along a line B1-B1 in FIG. 7A;

FIG. 7C is a plan view of an occupant load sensor in accordance withfurther the other example of the first embodiment;

FIG. 7D is a cross sectional view along a line D-D in FIG. 7C;

FIG. 8A is an explanatory view of an attachment of the occupant loadsensor in accordance with the first embodiment;

FIG. 8B is a cross sectional view along a line B2-B2 in FIG. 9A;

FIG. 9B is a side elevational view of a seat rail in accordance with amodified example of the first embodiment;

FIG. 9A is a cross sectional view along a line A4-A4 in FIG. 9B;

FIG. 10B is a side elevational view showing a state in which theoccupant load sensor in accordance with the modified example of thefirst embodiment is attached to a seat rail in accordance with the otherexample;

FIG. 10A is a cross sectional view along a line A5-A5 in FIG. 10B;

FIG. 11A is a side elevational view showing a state before an occupantload sensor in accordance with a second embodiment is attached to a seatrail;

FIG. 11B is a side elevational view showing a state after beingattached;

FIG. 12B is a side elevational view showing a state in which an occupantload sensor in accordance with a modified example of the secondembodiment is attached to the seat rail;

FIG. 12A is a cross sectional view along a line A6-A6 in FIG. 12B;

FIG. 13A is a side elevational view showing a state before the occupantload sensor in accordance with the modified example of the secondembodiment is attached to the seat rail;

FIG. 13B is a side elevational view showing a state after beingattached;

FIGS. 14A and 14B are explanatory views showing an attached position ofthe occupant load sensor with respect to the seat;

FIG. 14C is an explanatory view showing an occupant load sensor inaccordance with a third embodiment;

FIG. 15A is a side elevational view of an occupant load sensor inaccordance with a prior art; and

FIG. 15B is a cross sectional view along a line B4-B4 in FIG. 15A.

BEST MODE FOR CARRYING OUT THE INVENTION

A description will be given below of an occupant load sensor inaccordance with an embodiment of the present invention with reference tothe accompanying drawings.

First Embodiment

FIGS. 1 to 3 show an occupant load sensor 10 in accordance with a firstembodiment, FIG. 4 shows a state in which the occupant load sensor 10 isattached to a seat rail, and FIG. 14A shows an attached position of theoccupant load sensor 10 with respect to a seat.

FIG. 14A is an explanatory view of a seat 50 in a plan view. A pair ofseat rails 40 are arranged below the seat 50. The occupant load sensor10 is arranged in four corners in an upper side of the seat rail 40.

FIG. 4B is a side elevational view of a seat rail 40 shown in FIG. 14Aas seen from an arrow B side, and FIG. 4A is a cross sectional viewalong a line A-A in FIG. 4B.

The seat rail 40 is constituted by an upper rail 42 and a lower rail 44,the lower rail 44 is fixed to a floor via a foot 46, and the upper rail42 is structured such as to be slidable on the lower rail 44. A bracket48 for attaching the seat is fixed onto the upper rail 42 via theoccupant load sensor 10.

FIG. 1A is a plan view of the occupant load sensor in accordance withthe first embodiment, FIG. 1B is a side elevational view, and FIG. 1C isa cross sectional view along a line C-C in FIG. 1A. FIG. 2A is a planview of a state in which a terminal box 16 is attached to the occupantload sensor in accordance with the first embodiment, and FIG. 2B is aside elevational view. FIG. 3A is an explanatory view of an attachmentof the occupant load sensor, and FIG. 3B is a cross sectional view alonga line B-B in FIG. 4A.

As shown in FIG. 3B showing the cross section along the line B-B in FIG.4A, the occupant load sensor 10 is constituted by a flange portion 20which is in surface contact with a lower surface of the upper rail (afloor side seat fixing member) 42 and is attached by a bolt 69, and abolt portion 30 which is formed in a vertical direction with respect tothe flange portion 20 and is attached to the bracket (a seat side fixingmember) 48 side via a nut 66.

As shown in FIG. 1C, in the flange portion 20, there are formed a pairof screw holes 22 for fixing the bolt 69, a recess portion 24 for fixingthe bolt portion 30, and a depression 26 in a lower portion of therecess portion 24. The depression 26 is formed for achieving a flatnessin a lower end surface of the screw hole 22.

The bolt portion 30 is structured by an upper end thread 32, a middlestage flange 34 and a lower stage flange 36. The thread 32 carries outfixation of the nut 66 and insertion of a collar 60 mentioned below. Themiddle stage flange 34 extending in a horizontal direction carries outsupport of the collar 60 mentioned below. A concentric groove 36 a isformed at an approximately center position of an upper surface of thelower stage flange 36 extending in a horizontal direction for generatinga microscopic deflection on a lower surface (a strain surface) 14 asmentioned below. A step portion 36 b for fitting into the recess portion24 of the flange portion 20 is formed in an outer peripheral side of alower surface of the lower stage flange 36. A connection portion shownby reference symbol E in the drawing between the step portion 36 b andthe flange portion 20 is welded by a laser welding. An air gap forarranging a pair of silicone sensors (strain sensors) 12 and sensor ICchips 13 is formed within the recess portion 24. A lower surface of thelower stage flange 36 structures the strain surface 14 to which thesensor 12 is attached. In other words, when a load in a verticaldirection is applied between the bolt portion 30 and the flange portion20, the strain surface 14 is deflected microscopically, and the sensor12 detects the deflection as a load. A signal line (not shown) isconnected to the sensor 12 via a terminal box 16 shown in FIG. 2. Inthis case, in this embodiment, the sensor 12 is arranged in the lowersurface of the lower stage flange 36, however, it can be, of course,arranged in a bottom portion of the recess portion 24.

A description will be given of an attachment of the occupant load sensor10 with reference to FIG. 3A.

First, the bolt portion 30 of the occupant load sensor 10 is insertedthrough an opening 42 a of the upper rail 42 from a back surface side ofthe upper rail 42, and the flange portion 20 is fixed to the upper rail42 by a bolt 69. Next, the collar 60 is inserted through the thread 32of the bolt portion 30, and is supported by the middle stage flange 34.The collar 60 is constituted by a sleeve 60 a and a flange 60 b. On theother hand, a bush (a liner member) 62 constituted by a thin cylindricalliner is attached to a through hole 48 a of the bracket 48 for fittingto an inner surface. Further, as shown in FIG. 3B, the nut 66 is fixedto the thread 32 of the bolt portion 30 in a state in which the sleeve60 a of the collar 60 is inserted into the bush 62.

In this case, a gap larger than an assembly error is set between anouter periphery of the thread 32 of the bolt portion and an innerperiphery of the sleeve 60 a of the collar 60. In the same manner, a gaplarger than an assembly error is set between an outer periphery of thesleeve 60 a and an inner periphery of the bush 62. A height H of thesleeve 60 a is set slightly larger than a dimension obtained by adding athickness of the bush 62 to a thickness of the bracket 48.

In the first embodiment, the occupant load sensor 10 is fixed to thebracket 48 via the sleeve 60 a of the collar 60 arranged in an outerperiphery of the thread 32 of the bolt portion 32, and the bush 62interposed between the sleeve 60 a and the through hole 48 a of thebracket 48. Accordingly, the slight movement is allowed between the boltportion 30 and the bracket 48 to which the bolt portion 30 is fixed, onthe basis of the gap formed between the thread 32 and the sleeve 60 a,and the gap formed between the sleeve 60 a and the bush 62, and thesleeve 60 a slides along the inner surface of the bush 62, whereby it ispossible to cancel the force applied from the other directions than thevertical direction. Therefore, the load from the seat side is applied tothe sensor 12 in the vertical direction, and it is possible toaccurately detect the load. In particular, the seat rail 40 or the likeis deflected due to the load, and it is possible to accurately measureeven if the force is hard to be applied to the occupant load sensor 10in the vertical direction. Further, since the slight movement is allowedbetween the bolt portion 30 and the bracket 48 even if the accuracy ofthe attached position of the bracket 48 with respect to the seat rail 40is low, and the occupant load sensor 10 is attached in a state in whichthe force in the other directions than the vertical direction isapplied, the load from the seat side is applied to the sensor 12 in thevertical direction, and it is possible to accurately detect the load.

In particular, the occupant load sensor 10 is attached to the upper rail42 of the seat rail 40 while being in surface contact therewith by theflange portion 20, and the bolt portion 30 formed in the verticaldirection with respect to the flange portion 20 is attached to thebracket 48 via the nut 66. Accordingly, the load from the seat isapplied to the vertical direction, and it is possible to accuratelymeasure the load by the sensor 12. Further, it is possible to lower thehip point of the seat by receiving the flange portion 20 in the lowerside of the upper rail 42.

Further, in the first embodiment, since the flange 60 b of the collar 60is brought into contact with the lower surface of the bracket 48 towhich the bolt portion 30 is fixed and the upper surface of the middlestage flange 34, and generates the load in the axial (vertical)direction with respect to the sleeve 60 a, the load from the seat isapplied in the vertical direction, and it is possible to accuratelymeasure the load by the sensor. Further, the number of the parts isreduced, and it is easy to assemble. In this case, it is possible to usea sleeve provided with no flange as it is, in place of using the collar60.

FIGS. 5 and 6 show the other example of the mounted position of theoccupant load sensor 10 in accordance with the first embodiment. FIG. 5Bis a side elevational view showing a state in which the occupant loadsensor in accordance with the first embodiment is attached to a seatrail in accordance with the other example, and FIG. 5A is a crosssectional view along a line A2-A2 in FIG. 5B. FIG. 6B is a sideelevational view showing a state in which the occupant load sensor inaccordance with the first embodiment is attached to a seat rail inaccordance with further the other example, and FIG. 6A is a crosssectional view along a line A3-A3 in FIG. 6B.

In both of the other example shown in FIG. 5 and the other example shownin FIG. 6, the occupant load sensor 10 is arranged between the seat rail40 and the foot 46 fixing the seat rail 40 to the floor. In this case,in the other example shown in FIG. 5, the flange portion 20 of theoccupant load sensor 10 is arranged in an upper side of the lower rail44. In the other example shown in FIG. 6, the flange portion 20 isarranged in a lower side of the lower rail 44. In the other exampleshown in FIG. 5, since the flange portion 20 of the occupant load sensor10 is received within the seat rail 40, there is an advantage that thehip point of the seat can be lowered. In the other example shown in FIG.6, there is an advantage that it is easy to attach the occupant loadsensor 10.

In the occupant load sensor 10 shown in FIG. 1, the flange portion 20 isformed in an approximately oval shape, however, the flange portion 20may be formed in any other shapes. FIG. 7A is a plan view of an occupantload sensor in accordance with the other example of the firstembodiment, and FIG. 7B is a cross sectional view along a line B1-B1 inFIG. 7A. FIG. 7C is a plan view of an occupant load sensor in accordancewith further the other example of the first embodiment, and FIG. 7D is across sectional view along a line D-D in FIG. 7C.

In the other example shown in FIG. 7A, the flange portion 20 is formedin a circular shape. In further the other example shown in FIG. 7C, theflange portion 20 is formed in a quadrangular shape. In accordance withthe shapes shown in FIGS. 7A and 7C, it is possible to improve anattaching strength by increasing the number of the fixing bolt.

Modified Example of First Embodiment

FIG. 8 shows an occupant load sensor 10 in accordance with a modifiedexample of the first embodiment, and FIG. 9 shows a state in which theoccupant load sensor 10 is attached to the seat rail. FIG. 9B is a sideelevational view of the seat rail 40, and FIG. 9A is a cross sectionalview along a line A4-A4 in FIG. 9B. FIG. 8A is an explanatory view of anattachment of the occupant load sensor, and FIG. 8B is a cross sectionalview along a line B2-B2 in FIG. 9A.

The occupant load sensor in accordance with the first embodiment isfixed by the bolt 69. On the contrary, the occupant load sensor inaccordance with the modified example of the first embodiment is fixed bya shoulder bolt 68 and a bolt 69.

As shown in FIG. 8B, the occupant load sensor 10 is constituted by aflange portion 20 which is in surface contact with a lower surface ofthe lower rail (the seat side fixing member) 44 and is attached by theshoulder bolt 68 and the bolt 69, and a bolt portion 30 which is formedin a vertical direction with respect to the flange portion 20 and isattached to the foot (the floor side seat fixing member) 46 side via thenut 66.

A description will be given of an attachment of the occupant load sensor10 with reference to FIG. 8A.

First, the occupant load sensor 10 is fixed to the lower rail 44 side byinserting the bolt 69 and the shoulder bolt 68 from the upper surfaceside of the lower rail 44 via through holes 44 a and 44 b of the lowerrail 44 and screwing into the screw hole 22 (refer to FIG. 1C) of theoccupant load sensor 10. In this case, the bolt 69 is constituted by ahead 69 a and a thread 69 b, and the shoulder bolt 68 is constituted bya head 68 a, a step portion 68 c and a thread 68 b. A height F of thestep portion 68 c of the shoulder bolt 68 is formed 0.5 mm higher than athickness G of the lower rail 44. In this case, the through hole 44 a ofthe lower rail 44 is formed larger than an outer diameter of the stepportion 68 c of the shoulder bolt 68, and the opening 44 b is formedlarger than an outer diameter of the thread 69 b of the bolt 69.

Next, the collar 60 is inserted to the thread 32 of the bolt portion 30,and is supported by the middle stage flange 34. The collar 60 isconstituted by the sleeve 60 a and the flange 60 b. On the other hand, abush (a liner member) 62 constituted by a thin cylindrical liner isattached to a through hole 46 a of the foot 46 for fitting to an innersurface. Further, as shown in FIG. 8B, the nut 66 is fixed to the thread32 of the bolt portion 30 in a state in which the sleeve 60 a of thecollar 60 is inserted into the bush 62.

In this case, the flange portion is firmly fixed to the lower rail 44 ina side to which the bolt 69 is attached. On the other hand, an air gap(a gap) C (0.5 mm) corresponding to a difference between the height F ofthe step portion 68 c and the thickness G of the lower rail 44 mentionedabove is formed in a side to which the shoulder bolt 68 is attached. Theslight movement is allowed between the fixed position of the flangeportion 20 in the side of the shoulder bolt 68 and the lower rail 44, onthe basis of the gap C, and it is possible to make the torsion of thelower rail 44 hard to be transmitted to the occupant load sensor 10.Accordingly, the load from the seat side is applied to the sensor in thevertical direction, and it is possible to accurately detect the load.Further, since the slight movement is allowed between the fixed positionof the flange portion 20 in the side of the shoulder bolt 68 and thelower rail 44 even if the accuracy of the attached position of the lowerrail 44 with respect to the foot 46 is low, and the occupant load sensoris attached in a state in which the force in the other direction thanthe vertical direction is applied, the load from the seat side isapplied to the sensor in the vertical direction, and it is possible toaccurately detect the load.

In the modified example of the first embodiment, since the flange 60 bof the collar 60 is brought into contact with the lower surface of thelower rail 44 to which the bolt portion 30 is fixed and the uppersurface of the middle stage flange 34, and the load in the axial(vertical) direction is generated with respect to the sleeve 60 a, theload from the seat is applied in the vertical direction, and it ispossible to accurately measure the load by the sensor. Further, thenumber of the parts is reduced, and it is easy to assemble. In thiscase, it is possible to employ the sleeve provided with no flange as itis, in place of using the collar 60.

FIG. 10B is a side elevational view showing a state in which theoccupant load sensor in accordance with the modified example of thefirst embodiment is attached to a seat rail in accordance with the otherexample, and FIG. 10A is a cross sectional view along a line A5-A5 inFIG. 10B.

In the other example shown in FIG. 10, the occupant load sensor 10 isarranged between the seat rail 40 and the foot 46 fixing the seat rail40 to the floor in the same manner as the modified example of the firstembodiment. In this case, in this other example, the flange portion 20of the occupant load sensor 10 is arranged in the upper side of thelower rail 44. In this other example, since the flange portion 20 of theoccupant load sensor 10 is received within the seat rail 40, there is anadvantage that the hip point of the seat can be lowered.

Second Embodiment

FIG. 11A is a side elevational view showing a state before an occupantload sensor in accordance with a second embodiment is attached to a seatrail, and FIG. 11B is a side elevational view showing a state afterbeing attached. As described above with reference to FIG. 3, in thefirst embodiment, the occupant load sensor 10 is fixed by interposingthe bush 62 between the collar 60 and the through hole 48 a of thebracket 48. On the contrary, in the second embodiment, a flat washer 64is interposed between the bracket 48 and the nut 66, in place of thebush. In this case, since the occupant load sensor 10 in accordance withthe second embodiment and the occupant load sensor 10 in accordance withthe first embodiment have the same structure, a description thereof willbe omitted while referring to FIGS. 1 and 2.

In accordance with the second embodiment, the occupant load sensor 10 isfixed to the bracket 48 via the sleeve 60 a of the collar 60 arrangedbetween the thread 32 of the bolt portion 30 and the through hole 48 aof the bracket 48, and the flat washer 64 inserting the sleeve 60 atherethrough and interposed between the bracket 48 and the nut 66.Accordingly, a slight movement is allowed between the bolt portion 30and the bracket 48 to which the bolt portion 30 is fixed, on the basisof a gap formed between the thread 32 of the bolt portion 30 and thesleeve 60 a, and a gap formed between the bracket 48 interposing theflat washer 64 therein and the nut 66, and it is possible to cancel theforce applied from the other directions than the vertical direction.Accordingly, the load from the seat side is applied to the sensor 12(refer to FIG. 1C) in the vertical direction, and it is possible toaccurately detect the load. Further, since the slight movement isallowed between the bolt portion 30 and the bracket 48 even if theaccuracy of the attaching position of the bracket 48 with respect to theseat rail 40 is low, and the occupant load sensor 10 is attached in astate in which the force in the other directions than the verticaldirection is applied, the load from the seat side is applied to thesensor 12 in the vertical direction, and it is possible to accuratelydetect the load.

Modified Example of Second Embodiment

FIG. 12B is a side elevational view showing a state in which an occupantload sensor in accordance with a modified example of the secondembodiment is attached to the seat rail, and FIG. 12A is a crosssectional view along a line A6-A6 in FIG. 12B. The occupant load sensorin accordance with the second embodiment is fixed to the seat rail bythe bolt 69. On the contrary, the occupant load sensor in accordancewith the modified example of the second embodiment is fixed to the seatrail by the shoulder bolt 68 and the bolt 69. In the modified example ofthe second embodiment, the occupant load sensor 10 is arranged betweenthe upper rail 42 of the seat rail 40 and the bracket 48 fixing theseat. FIG. 13A is a side elevational view showing a state before theoccupant load sensor in accordance with the modified example of thesecond embodiment is attached to the seat rail, and FIG. 13B is a sideelevational view showing a state after being attached. FIG. 13Bcorresponds to the cross sectional view along a line B3-B3 in FIG. 12A.

Third Embodiment

A description will be given of an occupant load sensor in accordancewith a third embodiment of the present invention with reference to FIG.14. FIGS. 14A and 14B are explanatory views showing an attached positionof the occupant load sensor with respect to the seat in accordance withthe first embodiment, and FIG. 14C is an explanatory view showing theoccupant load sensor in accordance with the third embodiment.

In the occupant load sensor 10 in accordance with the first embodiment,as shown in FIG. 14B, in the case that the attached position of a pairof seat rails 40 is largely deflected, the occupant load sensor 10 isattached in a state in which the force in the other directions than thevertical direction is applied, so that it is hard to accurately detectthe load. On the contrary, the occupant load sensor 10 in accordancewith the third embodiment is structured such that a pair of seat rails40 are connected via a connection bracket 52, thereby preventing arelative attached position from being deflected. Accordingly, it ispossible to prevent the occupant load sensor from being attached in astate in which the force in the other directions than the verticaldirection is applied.

In accordance with the third embodiment, the occupant load sensor 10 canbe arranged at various positions in the same manner as that of the firstembodiment which is described above with reference to FIGS. 4 to 6.Further, it is possible to comparatively accurately measure even byusing the occupant load sensor 110 in accordance with the prior artwhich is described above with reference to FIG. 15.

1. An occupant load sensor interposed between a floor side seat fixingmember and a seat side fixing member and provided for measuring a loadof an occupant sitting on a seat, comprising: a flange portion which isattached to one of said floor side seat fixing member and said seat sidefixing member while being in surface contact therewith; a bolt portionwhich is formed in a vertical direction with respect to said flangeportion, and is attached to the other of said floor side seat fixingmember and said seat side fixing member via a nut; and a sensor which isarranged in a strain surface provided between said flange portion andsaid bolt portion, and is provided for detecting a load applied to saidbolt portion in an axial direction.
 2. An occupant load sensorinterposed between a floor side seat fixing member and a seat sidefixing member and provided for measuring a load of an occupant sittingon a seat, wherein said occupant load sensor comprising: a fixingportion which is attached to one of said floor side seat fixing memberand said seat side fixing member; a bolt portion which is inserted to athrough hole in the other of said floor side seat fixing member and saidseat side fixing member and is attached via a nut; and a sensor which isarranged in a strain surface provided between said fixing portion andsaid bolt portion, and is provided for detecting a load applied to saidbolt portion in an axial direction, and wherein said occupant loadsensor is fixed to the other of said floor side seat fixing member andsaid seat side fixing member via a sleeve arranged in an outer peripheryof said bolt portion, and a liner member interposed between said sleeveand the through hole in the other of said floor side seat fixing memberand said seat side fixing member.
 3. An occupant load sensor interposedbetween a floor side seat fixing member and a seat side fixing memberand provided for measuring a load of an occupant sitting on a seat,wherein said occupant load sensor comprising: a flange portion which isattached to one of said floor side seat fixing member and said seat sidefixing member while being in surface contact therewith; a bolt portionwhich is formed in a vertical direction with respect to said flangeportion and is attached to the other of said floor side seat fixingmember and said seat side fixing member via a nut; and a sensor which isarranged in a strain surface provided between said flange portion andsaid bolt portion, and is provided for detecting a load applied to saidbolt portion in an axial direction, and wherein said occupant loadsensor is fixed to the other of said floor side seat fixing member andsaid seat side fixing member via a sleeve arranged in an outer peripheryof said bolt portion, and a bush interposed between said sleeve and athrough hole in the other of said floor side seat fixing member and saidseat side fixing member.
 4. An occupant load sensor interposed between afloor side seat fixing member and a seat side fixing member and providedfor measuring a load of an occupant sitting on a seat, wherein saidoccupant load sensor comprising: a flange portion which is attached toone of said floor side seat fixing member and said seat side fixingmember while being in surface contact therewith; a bolt portion which isformed in a vertical direction with respect to said flange portion andis attached to the other of said floor side seat fixing member and saidseat side fixing member via a nut; and a sensor which is arranged in astrain surface provided between said flange portion and said boltportion, and is provided for detecting a load applied to said boltportion in an axial direction, and wherein said occupant load sensor isfixed to the other of said floor side seat fixing member and said seatside fixing member via a sleeve arranged between said bolt portion and athrough hole in the other of said floor side seat fixing member and saidseat side fixing member, and a flat washer inserting said sleevetherethrough and interposed between the other of said floor side seatfixing member and said seat side fixing member and a nut.
 5. An occupantload sensor as claimed in claim 2, wherein said sleeve is a part of thecollar.
 6. An occupant load sensor as claimed in claim 1, wherein a pairof said floor side seat fixing members are connected via a bracket. 7.An occupant load sensor interposed between a floor side seat fixingmember and a seat side fixing member and provided for measuring a loadof an occupant sitting on a seat, comprising: a flange portion which isprovided with a plurality of screw holes for fastening by bolts and isattached to one of said floor side seat fixing member and said seat sidefixing member while being in surface contact therewith; an attachingportion which is formed in a vertical direction with respect to saidflange portion, and is attached to the other of said floor side seatfixing member and said seat side fixing member; and a sensor which isprovided for detecting a load applied to said attaching portion in anaxial direction, wherein at least one of a plurality of screw holesprovided in said flange portion is fastened by bolts so as to allow amotion between said flange portion and one of said floor side seatfixing member and said seat side fixing member.
 8. An occupant loadsensor interposed between a floor side seat fixing member and a seatside fixing member and provided for measuring a load of an occupantsitting on a seat, comprising: a flange portion which is provided with aplurality of screw holes for fastening by bolts and is attached to oneof said floor side seat fixing member and said seat side fixing memberwhile being in surface contact therewith; a bolt portion which is formedin a vertical direction with respect to said flange portion, and isattached to the other of said floor side seat fixing member and saidseat side fixing member via a nut; and a sensor which is provided fordetecting a load applied to said bolt portion in an axial direction,wherein one of a plurality of screw holes provided in said flangeportion is fixed by a shoulder bolt provided with a step portion higherthan a thickness of one of said floor side seat fixing member and saidseat side fixing member, whereby an air gap is provided between a headof the shoulder bolt and one of said floor side seat fixing member andsaid seat side fixing member.
 9. An occupant load sensor as claimed inclaim 8, wherein said occupant load sensor is fixed to the other of saidfloor side seat fixing member and said seat side fixing member via asleeve arranged in an outer periphery of said bolt portion, and a bushinterposed between said sleeve and a through hole in the other of saidfloor side seat fixing member and said seat side fixing member.
 10. Anoccupant load sensor as claimed in claim 8, wherein said occupant loadsensor is fixed to the other of said floor side seat fixing member andsaid seat side fixing member via a sleeve arranged between said boltportion and a through hole in the other of said floor side seat fixingmember and said seat side fixing member, and a flat washer insertingsaid sleeve therethrough and interposed between the other of said floorside seat fixing member and said seat side fixing member and the nut.11. An occupant load sensor as claimed in claim 9, wherein said sleeveis a part of the collar.
 12. An occupant load sensor as claimed in claim3, wherein said sleeve is a part of the collar.
 13. An occupant loadsensor as claimed in claim 4, wherein said sleeve is a part of thecollar.